Vulcanization accelerator



Patented May 27, 1941 voncmz ArroN ACCELERATOR Robert L. Sibley, Nitro, W. Va., assignor to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware No Drawing.

1937, Serial No.

Original application December 23,

181,368. Divided and this application July 28, 1939, Serial No. 287,136

16 Claims.

The present invention relates to a new and improved class of rubber vulcanization accelerators, to a process of vulcanizing rubber or a rubber containing material, and to the vulcanized rubber products obtained with the aid of said new and improved vulcanization accelerators.

The accelerators of the present invention are the products obtainable by reacting a cyclohexylamine with an aldehyde and further reacting the product so obtained with carbon bisulfide. anhydrous sodium sulfate. 19 parts by weight The use of products obtained by reacting certain (substantially 0.25 molecular proportions) of amines with an aldehyde and further reacting carbon bisulfide were then added to the above the product so formed with carbon bisulfide is described oil. The reaction took place immewell-known to the rubber vulcanization art and diately and the desired reaction product Was some of the accelerators employed by the trade obtained as a clear yellow oil. are of this type. The use of the accelerators of As a further specific example of the invention the present invention, however, represents an N-methyl cyclohexylamine was reacted in a manimprovement over the prior art. As illustrative ner analogous to that described above. 57 parts of this improvement the product obtained by by weight (substantially 0.5 molecular proporreacting N-methyl cyclohexylamine first with 20 tions) of N-methyl cyclohexylamine and 28 parts formaldehyde and then reacting thealdehydeby weight of approximately 37% formaldehyde amine with carbon bisulfide has been found on (substantially 0.28 molecular proportions) were testing to give a faster cure at a lower temperamixed together in a suitable container. The ture than the amine-aldehyde, carbon bisulfide temperature of the mixture was kept below 15 0. reaction products heretofore employed, as for and the mixture was stirred for one hour and example piperidine reacted with formaldehyde allowed to stand until it had separated into two and further reacted with carbon bisulfide. Furlayers. The waterlayer Was removed and the ther advantages of the preferred class of accelresidue dried over anhydrous sodium sulfate and erators will be apparent from the examples treated'with 19 parts by weight (substantially hereinafter Shown- 3 0.25 molecular'proportions) of carbon bisulfide. yp al e amples of cyclohexylam n s W c The ensuingreaction was immediate and vigmay be employed in the preparation of the new orous, the temperature rising rapidly from 15 C. and preferred class of accelerators are cyclo to 30 C, (The desired reaction product was I h xyl m n Nm hy1 y lohexylamine, N-ethyl thereby obtained as a Viscous oil. An analysis cyclohexylamine, N-butyl cyclohexylamine, N- for sulfur in the, reaction product gave an aver myl cy l h xyl i i y lo xylamine, N- age of 20.55% and for nitrogen an average of benzyl cyclohexylamine, N-hexahydro benzyl ,75%, r cifclohexylaminei N-methyl methyl cyclohexylaf The above described materials prepared from mine and ethyl qyclohexylamine- N-methylcyclohexylamine and N-ethyl cyclo- A cyclohevlamme as Illustrated above may 40 hexylamine were compounded into a rubber latex be reacted with an aldehyde, preferably formalmix'as follows} dehyde, and then with carbon bisulfide to form the new and preferred class of accelerators. Ste k Examples of aldehydes which may be so employed c are formaldehyde, acetaldehyde, and their poly- A B meric forms, propionaldehyde, butylaldehyde, isovaleric aldehyde, acrolein aldehyde, croton aldehyde, aldol benzameh de, cinnamic alde yde tit3%if??iiiii::::::::::::::::::"'::""::; and furfumldehyde' e ibll"idt'iiii ifffEiiFidiiHhHd' Specific embodiment Wh ch iS intended forlrigldghyde, further rzact ed witl? carbon bi-V 0 Q to e illustrative of the invention and not limitative of the scope thereof, one of the preferred gi i 'figl cigl i dgf r3$555553 class of accelerators was prepared from N-ethyl "bisulfide cyclohexylamine. 64 parts by weight of N-ethyl cyclohexylamine (substantially 0.5 molecular pr'oportions) and 28 parts by weight of approximately 37% formaldehyde (substantially 0.28 molecular proportions) were mixed together in a suitable container, keeping the temperature of the mixture below 15 C., and stirred for one hour. The mixture was then allowed to stand overnight at room temperature at which time it had separated into two layers. The water layer was removed and the oil residue dried over "The rubber mixes so compounded Were poured Table I Cured in air at 158 F. (70 C.).

Modulus of elasticity in Cure lbs/in. at elongations of Tensile at Ult.

break in Elong. T lbs/in. percent ime m a Stock minutes 500% 700% e A Uncured 640 2470 6130 930 B Uncured 720 2900 6280 910 A 10 630 2450 6190 935 B 10 690 2820 6200 905 A 20 640 2430 6160 935 B 20 700 2860 6050 900 A 30 600 2450 6060 930 B 30 730 2810 6220 905 A 50 630 2440 6020 930 B 50 740 2830 6230 910 A 70 620 2460 6190 935 B 70 760 2970 6470 900 A 90 600 2450 6190 940 B 90 770 3000 6550 910 Table II Cured in water at 100 C.

Modulus of elasticity in Cure lbs/inf at elongations ol Tensile at Ult.

break in elong., T lbs/in. percent ime in Stock minutes 500% 700% A Uncured 600 2200 6030 940 B Uncured 690 2700 6360 900 A 3 610 2220 6280 945 B 3 710 2720 6430 900 A 5 600 2110 5920 925 B 5 720 2740 6180 885 A 610 2120 6070 930 B 10 710 2740 6400 S85 A 590 2210 6080 920 B 15 720 2770 5950 850 A 600 2220 6070 915 B 20 740 2790 5960 855 A 40 610 2290 5750 880 B 40 810 2930 5800 845 The above data show the accelerating properties of the preferred class of materials, for example the reaction product of N-methylcyclohexylamine and formaldehyde further reacted with carbon bisulfide, when employed in an aqueous rubber dispersion. The data show that the new accelerators are very fast, fiat-curing accelerators. Thus the three day drying at room temperature has resulted in a set-up? of the rubber stock and said drying alone produced a high modulus and tensile stock from which it is evident that the new class of acceleratorsv are active at temperatures even below 70 C. The modulus and tensile properties remain nearly constant after curing in air at 70 C. and in water at 100 C. as shown.

As further specific embodiments of the invention, other typical examples of the preferred class of materials were prepared wherein the amine was initially reacted with the aldehyde and the product so formed further reacted with carbon bisulfide. Thus, by the method hereinbefore described N-ethyl cyclohexylamine was reacted with butylaldehyde and carbon bisulfide and N-benzyl cyclohexylamlne was reacted with formaldehyde and carbon bisulfide. The proportions of the reactants employed were substantially two molecular proportions of amine, one molecular proportion of aldehyde and an .amine were incorporated into a typical rubber stock comprising Stock Reaction product of N-methyl cyclohexylamine and formaldehyde further reacted with carbon bisulfide Reaction product of N-ethyl cyclohexylamine and butylaldehyde further reacted with carbon bisulfide Reaction product of N-benzyl cylohexylamino and formaldehyde further reacted with carbon bisulfide The stocks so compounded were vulcanized at the temperature of 5 pounds steam pressure per square inch and the following modulus and tensile properties obtained on testing the cured rubber product.

Table III Modulus of elasticity Cure in lbs/in. at elongations of Tensile at Ult.

break in elong, T lbs/in. percent line 111 Stock minutes 300% 500% C 10 140 250 2725 900 D 10 165 1800 940 E 10 230 2325 920 C 20 185 415 3850 840 D 20 315 2700 880 E 20 150 360 3525 885 O 30 225 590 4500 805 D 30 375 3150 830 E 30 420 3950 850 C 60 360 1300 4550 690 D 60 290 850 3825 720 E 60 260 720 4400 780 The above data show that the preferred class of accelerators give a fast cure at the temperature of five pounds of steam pressure per square inch.

As further specific embodiments of the invention dicyclohexlamine was reacted with formaldehyde and the product so formed reacted with carbon bisulfide; cyclohexylamine was reacted with formaldehyde and the product so formed reacted with carbon bisulfide; cyclohexylamine was reacted with acetaldehyde and the product so formed reacted with carbon bisulfide and the materials so prepared found on testing in a typical rubber stock to exhibit desirable accelerating properties.

The present invention is not limited to the specific examples hereinbefore set forth wherein the preferred accelerators are employed. Other proportions of the reactants may be employed in the preparation of the preferred class of accelerators, for example an excess of either one or both the aldehyde and carbon bisulfide may be utilized and any reacted materials removed by any convenient means from the final product.

Other ratios of the compounding ingredients than those mentioned in the examples as well as other well-known fillers, pigments and the like may be employed in the production of various types of rubber compounds and are apparent to those skilled in the art to which the invention pertains. The present invention is limited solely by the following claims.

This is a division of my co-pending application Serial No. 181,368 filed December 23, 1937.

What is claimed is:

1. The new chemical product comprising a reaction product of a cyclohexylamine containing at least one hydrogen atom on the amino nitrogen atom with an aldehyde combined in the ratio of two molecular proportions of amine and one molecular proportion of aldehyde, further reacted with carbon bisulfide.

2. The new chemical product comprising a reaction product of a mono N-alkyl cyclohexylamine with an aldehyde combined in the ratio of two molecular proportions of amine and one molecular proportion of aldehyde, further reacted with carbon bisulfide.

3. The new chemical product comprising a reaction product of a mono N-alkyl cyclohexylamine wherein the said alkyl group contains less than six carbon atoms, with an aliphatic aldehyde combined in the ratio of two molecular proportions of amine and one molecular proportion of aldehyde, further reacted with carbon bisulfide.

4. The new chemical product comprising a reaction product of a mono N-alkyl cyclohexylamine wherein the said alkyl group contains less than six carbon atoms, with an aliphatic aldehyde containing less than six carbon atoms combined in the ratio of two molecular proportions of amine and one molecular proportion of aldehyde, further reacted with carbon bisulfide.

5. The new chemical product comprising a reaction product of a mono N-alkyl cyclohexylamine wherein the said alkyl group contains less than six carbon atoms, with formaldehyde combined in the ratio of two molecular proportions of amine and one molecular proportion of formaldehyde, further reacted with carbon bisulfide.

6. The new chemical product comprising a reaction product of N -methyl cyclohexylamine, with formaldehyde combined in the ratio of two molecular porportions of amine and one molecular propportion of formaldehyde, further reacted with carbon bisulfide.

7. The new chemical product comprising a reaction product cf N -ethyl cyclohexylamine with formaldehyde combined in the ratio of two molecular proportions of amine and one molecular proportion of formaldehyde, further reacted with carbon bisulfide.

8. The new chemical product comprising a reaction product of N-benzyl cyclohexylamine with formaldehyde combined in the ratio of two molecular proportions of amine and one molecular proportion of formaldehyde, further reacted with carbon bisulfide.

9. The method of preparing a new chemical product comprising initially reacting a cyclohexylamine containing at least one hydrogen atom on the amino nitrogen atom with an aldehyde to produce a product combined in the ratio of two molecular proportions of amine and one molecular proportion of aldehyde and further reacting the product so obtained with carbon bisulfide.

10. The method of preparing a new chemical product comprising initially reacting a mono -alkyl cyclohexylamine with an aldehyde to produce a product combined in the ratio of two molecular proportions of amine and one molecular proportion of aldehyde and further reacting the product so obtained with carbon bisulfide.

11. The method of preparing a new chemical product comprising initially reacting a mono N-alkyl cyclohexylamine wherein the said alkyl group contains less than six carbon atoms with an aliphatic aldehyde to produce a product combined in the ratio of two molecular proportions of amine and one molecular proportion of aldehyde and tained with carbon bisulfide.

12. The method of preparing a new chemical product comprising initially reacting a mono N-alkyl cyclohexylamine wherein the said alkyl group contains less than six carbon atoms, with an aliphatic aldehyde containing less than six carbon atoms to produce a product combined in the ratio of two molecular proportions of amine and one molecular proportion of aldehyde and further reacting the product so obtained with carbon bisulfide.

13. The method of preparing a new chemical product comprising initially reacting a mono -alkyl cyclohexylamine wherein the said alkyl group contains less than six carbon atoms, with formaldehyde to produce a product combined in the ratio of two molecular proportions of amine and one molecular proportion of formaldehyde and further reacting the product so obtained with carbon bisulfide.

14. The method of preparing a new chemical product comprising initially reacting N-methyl cyclohexylamine with formaldehyde to produce a product combined in the ratio of two molecular proportions of amine and one molecular proportion of formaldehyde and further reacting the product so obtained with carbon bisulfide.

15. The method of preparing a new chemical product comprising initially reacting N-ethyl cyclohexylamine with formaldehyde to produce a product combined in the ratio of two molecular proportions of amine and one molecular proportion of formaldehyde and further reacting the product so obtained with carbon bisulfide.

16. The method of preparing a new chemical product comprising initially reacting N-benzyl cyclohexylamine with formaldehyde to produce a product combined in the ratio of two molecular proportions of amine and one molecular tion of formaldehyde and further reacting the product so obtained with carbon bisulfide.

ROBERT L. SIBLEY.

further reacting the product so ob-. 

